In Canada, common law is AFAIK a common occurence and recognized by most provinces. The general rumour is that after 6 months cohabitation, you acquire similar rights to a married couple. It’s a bit more complicated, because marriage is a Canadian federal institution and so separation in common law is convered by provincial law, official divorce by federal.
Worse, if you act in any way like a parent to her kids, you can be liable for child support even though they are not yours.
the “Homestead Acts” of the various western provinces IIRC were so named because they provided protection for a spouse in the days when the guy would come home drunk and tell her “Honey, I lost the farm in a poker game - we’re moving”. You cannot sell, mortgage, or otherwise unload/risk your family home without the consent of your partner who must have independent legal advice before she signs her consent.
I assume if a state in the US does not accept common-law relationships as meaning anything, then of course tehre are unlikely to be any similar legalities around the relationship. Considering the history of “palimony” suits in the media, I assume some states do have the rules. Living in a federal territory complicates it - what are their rules?
Generally, in Canadian provinces, the Landlord-tenat act does not apply unless you are renting (paying specific amount for specific space) for a self-contained dwelling. it is not intended for shared accomodation arrangements. Rooming houses and other such arrangements are handled differently, and due to the types that live in rooming houses plus the oppportunity for exploitation or slumliness, here most rooming houses need special licensing and inspections; so she’s not going to qualify as a roomer. Your DC mileage may vary.
Ontario especially had some wildly bizzarre landlord-tenant rules that have been exploited; say that someone moves in with a legal tenant (landlord can’t stop it), then when the original tenant moves out, claims to be the official tenant; the landlord ahs a tenant now with no ability to screen or deny that person, and evictions are very hard to get.
A lot depends on the official paperwork. If you own the house, and there’s no common law rules, she’s SOL. However, if she’s been contributing to your mortgage (i.e. helping you to buy your house then a good lawyer might turn that into a claim, at the least, for payback - which might be cheaper to pay than fight. After all, fair is fair; if she helped pay your mortgage or freed up your money to pay down the mortgage by paying the electricity and water…